Cu\(_2\) O has a cubic crystal structure with inversion symmetry.
The cuprous oxide is a direct band-gap semiconductor with monovalent Cu\(^{+}\)  and a large band gap of \(\sim \) 2 eV [1]}.
Excitons in the optical spectra have attracted much attention [2]}.
The nature of Rydberg excitons and possible exciton Bose-Einstein condensation have been explored in Cu\(_2\) O [3]}, [4]}.
